The present invention relates to an ohmic contact and a method of forming an ohmic contact and more specifically to forming an ohmic contact of an indium gallium arsenide alloy on a body of a single crystal n-type or p-type gallium arsenide of high resistivity.
In the past, the methods for forming ohmic contacts to high resistivity gallium arsenide resulted in a variation of unwanted effects. Most of these unwanted effects were the result of depositing the contact mixture on the body of gallium arsenide at high temperatures. High temperature deposition causes greater surface disassociation of the gallium arsenide body and exaggerates the effect of the diffusion of impurities into the gallium arsenide body due to background contamination, at times causing a resistive interface. Excessive heating of a device is caused by a resistive interface. A resistive interface is a particularly serious problem in a Gunn oscillator where it can lower the oscillator's efficiency and vary its output frequency.
Therefore, it would be most desirable in the field of semiconductors to be capable of forming an ohmic contact on a body of n-type or p-type, high resistivity gallium arsenide at a low deposition temperature.